Menu

Thoracolumbar Spine & Deformity MCQs

Practice Set 15 of 49

This practice set contains high-yield board review questions covering key concepts in Thoracolumbar Spine & Deformity. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 281

Topic: Thoracolumbar Spine & Deformity

A 65-year-old female is diagnosed with L4-L5 degenerative spondylolisthesis. Which of the following anatomic variations is the most significant predisposing risk factor for developing this specific condition?

. Coronal orientation of the facet joints
. Sagittal orientation of the facet joints
. Congenital pars interarticularis defect
. Unilateral sacralization of L5
. Short pedicle syndrome

Correct Answer & Explanation

. Sagittal orientation of the facet joints

Explanation

A more sagittal orientation of the facet joints at L4-L5 reduces their mechanical resistance to anterior translation, predisposing the patient to degenerative spondylolisthesis.

Question 282

Topic: Thoracolumbar Spine & Deformity

A 70-year-old male undergoes evaluation for a significant adult spinal deformity. Standing full-length radiographs reveal a pelvic incidence (PI) of 60 degrees, a lumbar lordosis (LL) of 30 degrees, and a sagittal vertical axis (SVA) of +8 cm. If surgical correction is planned, what is the primary radiographic goal to improve postoperative health-related quality of life (HRQOL)?

. Achieve a lumbar lordosis (LL) of at least 80 degrees
. Correct the SVA to less than +5 cm and PI-LL mismatch to less than 10 degrees
. Reduce the pelvic incidence (PI) to match the lumbar lordosis (LL)
. Increase the pelvic tilt (PT) to greater than 25 degrees
. Ensure the thoracic kyphosis equals the pelvic incidence

Correct Answer & Explanation

. Correct the SVA to less than +5 cm and PI-LL mismatch to less than 10 degrees

Explanation

In adult spinal deformity, restoring sagittal balance is critical for optimizing patient outcomes. The key radiographic goals are an SVA < 50 mm, a Pelvic Tilt (PT) < 20 degrees, and a PI-LL mismatch of less than 10 degrees. Pelvic incidence is a fixed morphologic parameter and cannot be changed surgically.

Question 283

Topic: Thoracolumbar Spine & Deformity

A 14-year-old elite gymnast presents with progressive low back pain worsened by extension. Radiographs reveal a Grade 2 isthmic spondylolisthesis at L5-S1. Despite 6 months of rest and core strengthening, she has persistent severe pain. If surgical intervention is chosen, what is the most appropriate procedure?

. L5-S1 microdiscectomy
. L5 pars interarticularis repair (e.g., Scott wiring)
. L5 laminectomy without fusion
. L5-S1 posterior instrumented fusion
. Total disc replacement at L5-S1

Correct Answer & Explanation

. L5-S1 posterior instrumented fusion

Explanation

In a skeletally immature patient with symptomatic isthmic spondylolisthesis that fails conservative management, an in situ posterior spinal fusion is the treatment of choice. Direct pars repair is generally reserved for L4 or above with a defect but minimal slip, while L5-S1 defects with slips require fusion.

Question 284

Topic: Thoracolumbar Spine & Deformity

A 45-year-old male is undergoing evaluation for adult spinal deformity. The surgeon calculates the pelvic incidence (PI) to guide sagittal balance correction. Which of the following equations correctly defines pelvic incidence?

. Pelvic Incidence = Sacral Slope - Pelvic Tilt
. Pelvic Incidence = Lumbar Lordosis + Pelvic Tilt
. Pelvic Incidence = Thoracic Kyphosis - Sacral Slope
. Pelvic Incidence = Pelvic Tilt + Sacral Slope
. Pelvic Incidence = Sacral Slope x Pelvic Tilt

Correct Answer & Explanation

. Pelvic Incidence = Pelvic Tilt + Sacral Slope

Explanation

Pelvic incidence (PI) is a fixed morphologic parameter unique to each individual. It is mathematically defined as the sum of Pelvic Tilt (PT) and Sacral Slope (SS). PI = PT + SS.

Question 285

Topic: Thoracolumbar Spine & Deformity

A 7-year-old boy with a known diagnosis of Duchenne Muscular Dystrophy is brought to the orthopedic clinic. His parents report that he has been falling more frequently, struggles to climb stairs, and often uses his hands to push off his thighs when trying to stand up from the floor. On examination, you note enlarged calves that feel firm to palpation. Which of the following early signs of DMD is *least* likely to be observed in this patient's current presentation?

. Waddling gait
. Gower's sign
. Calf pseudohypertrophy
. Significant thoracolumbar scoliosis (Cobb angle > 40°)
. Difficulty running and jumping

Correct Answer & Explanation

. Significant thoracolumbar scoliosis (Cobb angle > 40°)

Explanation

Correct Answer: DThe case describes a 7-year-old boy presenting with several classic early signs of Duchenne Muscular Dystrophy (DMD): frequent falls, difficulty climbing stairs, Gower's sign (using hands to push off thighs to stand), and calf pseudohypertrophy. These are all characteristic features seen in early to intermediate stages of DMD, typically between ages 5 and 10.Significant thoracolumbar scoliosis (Cobb angle > 40°) is a major orthopedic complication of DMD, but it typically commences or rapidly progressesafter the loss of ambulation, which usually occurs around ages 10-12. While the patient is experiencing increased falls and difficulty with higher-level motor skills, he is still ambulatory. Therefore, a severe scoliosis of this magnitude is less likely to be observed at age 7 compared to the other listed early signs.Option A (Waddling gait):This is a characteristic broad-based, lordotic gait due to proximal muscle weakness, commonly seen in early DMD.Option B (Gower's sign):This pathognomonic maneuver, where the child uses their hands to 'walk up' their legs to stand, is a direct compensation for weak quadriceps and hip extensors and is a key early indicator mentioned in the vignette.Option C (Calf pseudohypertrophy):Enlargement of the calf muscles due to fatty and fibrous tissue infiltration is a classic early sign of DMD, also mentioned in the vignette.Option E (Difficulty running and jumping):Early loss of higher-level gross motor skills like running and jumping is a common manifestation of progressive muscle weakness in DMD.

Question 286

Topic: Thoracolumbar Spine & Deformity

A 9-year-old boy with Duchenne Muscular Dystrophy has been treated with oral deflazacort for several years. What is the primary orthopaedic benefit of continuous corticosteroid therapy in this patient population?

. Prevention of long bone fractures
. Curing the underlying genetic defect
. Prolongation of independent ambulation and delay of scoliosis onset
. Complete prevention of lower extremity contractures
. Rapid reversal of existing pseudohypertrophy

Correct Answer & Explanation

. Prolongation of independent ambulation and delay of scoliosis onset

Explanation

Corticosteroids like deflazacort prolong independent ambulation, preserve pulmonary function, and delay the onset and progression of scoliosis in patients with DMD. However, they increase the risk of osteopenia and fractures.

Question 287

Topic: Thoracolumbar Spine & Deformity

In a 10-year-old ambulatory boy with Duchenne Muscular Dystrophy, which of the following functional milestones is the strongest predictor that he will lose independent ambulation within the next 12 to 24 months?

. Development of a 15-degree scoliosis
. 10-meter walk time greater than 9 seconds
. Loss of ability to perform a standing broad jump
. Onset of the Gowers sign
. Elevation of serum creatine phosphokinase (CPK) above 5,000 U/L

Correct Answer & Explanation

. 10-meter walk time greater than 9 seconds

Explanation

A 10-meter walk/run time greater than 9 seconds strongly predicts the loss of independent ambulation within 1 to 2 years in boys with DMD. Other indicators include the inability to rise from the floor or climb stairs.

Question 288

Topic: Thoracolumbar Spine & Deformity

Daily systemic corticosteroid therapy is the gold standard medical management for Duchenne Muscular Dystrophy. What is the primary established orthopedic benefit of long-term glucocorticoid use in this patient population?

. Reversal of established dilated cardiomyopathy
. Increased cortical bone thickness preventing long-bone fractures
. Prolongation of independent ambulation by 2 to 3 years
. Complete prevention of structural scoliosis development
. Elimination of the need for Achilles tendon lengthening procedures

Correct Answer & Explanation

. Prolongation of independent ambulation by 2 to 3 years

Explanation

Corticosteroids (e.g., prednisone, deflazacort) are proven to prolong independent ambulation by an average of 2 to 3 years in DMD patients. They also delay the onset and reduce the severity of scoliosis, though they increase fracture risk due to osteopenia.

Question 289

Topic: Thoracolumbar Spine & Deformity

Long-term corticosteroid therapy is a standard of care for ambulatory boys with Duchenne Muscular Dystrophy. Which of the following best describes the established orthopedic effect of this systemic treatment?

. Prolongs independent ambulation and delays the onset of severe scoliosis
. Accelerates the development of equinovarus foot contractures
. Promotes earlier fusion of the capital femoral epiphysis
. Increases the peak curve magnitude of early-onset scoliosis
. Reduces the incidence of long bone extremity fractures

Correct Answer & Explanation

. Prolongs independent ambulation and delays the onset of severe scoliosis

Explanation

Corticosteroids (like deflazacort or prednisone) significantly preserve muscle strength in DMD. This prolongs the period of independent ambulation and notably delays both the onset and progression of scoliosis, though it does increase the risk of osteoporotic fractures.

Question 290

Topic: Thoracolumbar Spine & Deformity

Routine use of daily corticosteroids in patients with Duchenne muscular dystrophy has been shown to alter the natural history of the disease. Which of the following is a recognized orthopedic effect of this medical therapy?

. Decreases the risk of long bone fractures
. Increases the incidence of severe scoliosis requiring surgery
. Prolongs independent ambulation by 2 to 3 years
. Accelerates the progression of equinovarus contractures
. Promotes premature closure of the physes preventing limb length discrepancy

Correct Answer & Explanation

. Decreases the risk of long bone fractures

Explanation

Corticosteroid therapy in DMD prolongs independent ambulation, preserves respiratory function, and decreases the incidence of severe scoliosis. However, it increases the risk of vertebral and long bone fragility fractures.

Question 291

Topic: Thoracolumbar Spine & Deformity

Which of the following intervertebral levels is the most common site for degenerative spondylolisthesis?

. L2-L3
. L3-L4
. L4-L5
. L5-S1
. Cervicothoracic junction

Correct Answer & Explanation

. L4-L5

Explanation

Degenerative spondylolisthesis occurs most frequently at the L4-L5 level, largely due to the sagittal orientation of the facet joints at this level which provides less resistance to forward translation. Isthmic spondylolisthesis, conversely, is most common at L5-S1.

Question 292

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with persistent lower back pain exacerbated by extension. Radiographs reveal an L5-S1 isthmic spondylolisthesis. If this patient were to develop radicular symptoms due to the pseudarthrosis tissue in the pars defect, which nerve root is most likely to be compressed?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L5

Explanation

In an L5-S1 isthmic spondylolisthesis, hypertrophic fibrocartilaginous tissue at the pars interarticularis defect classically compresses the exiting L5 nerve root within the neural foramen.

Question 293

Topic: Thoracolumbar Spine & Deformity

A 45-year-old construction worker falls from scaffolding, sustaining an L1 burst fracture. He is neurologically intact. CT imaging shows 15 degrees of local kyphosis, 30% canal compromise, and an intact posterior tension band. According to the Thoracolumbar Injury Classification and Severity (TLICS) score, what is the recommended management?

. Posterior spinal instrumentation and fusion
. Anterior corpectomy and fusion
. Thoracolumbosacral orthosis (TLSO) bracing and early mobilization
. Percutaneous pedicle screw fixation without fusion
. Laminectomy and short-segment fusion

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing and early mobilization

Explanation

This patient has a TLICS score of 2 (Morphology: Burst = 1; Neuro: Intact = 0; PLC: Intact = 0). A score of 3 or less is an indication for nonoperative management, typically with a TLSO.

Question 294

Topic: Thoracolumbar Spine & Deformity

A 45-year-old male presents with a T12 burst fracture after a fall. According to the Thoracolumbar Injury Classification and Severity Score (TLICS), which of the following findings contributes the most points, strongly indicating the need for surgical stabilization?

. 50% loss of anterior vertebral body height
. Interpedicular widening on the AP radiograph
. Retropulsion of bone occupying 30% of the canal
. Disruption of the posterior ligamentous complex
. 15 degrees of focal kyphotic deformity

Correct Answer & Explanation

. Disruption of the posterior ligamentous complex

Explanation

In the TLICS system, the integrity of the posterior ligamentous complex (PLC) is a critical determinant of mechanical stability. A definite PLC disruption scores 3 points, which, when combined with a burst fracture morphology (1 or 2 points), generally pushes the total score to >4, indicating operative management.

Question 295

Topic: Thoracolumbar Spine & Deformity

A 16-year-old gymnast presents with persistent lower back pain. Radiographs reveal a pars interarticularis defect with a 25% anterior slip of L5 on S1. Which of the following best describes the classification of this spondylolisthesis?

. Dysplastic
. Isthmic
. Degenerative
. Traumatic
. Pathologic

Correct Answer & Explanation

. Isthmic

Explanation

Isthmic spondylolisthesis (Wiltse Type II) is caused by a stress fracture or defect in the pars interarticularis (spondylolysis). It is highly prevalent in adolescent athletes subjected to repetitive lumbar hyperextension, such as gymnasts and football linemen.

Question 296

Topic: Thoracolumbar Spine & Deformity

A 45-year-old male sustains an L1 burst fracture after a fall from a roof. He is neurologically intact. MRI demonstrates an intact posterior ligamentous complex. His Thoracolumbar Injury Classification and Severity (TLICS) score is calculated as 2. What is the most appropriate evidence-based recommendation?

. Posterior instrumented spinal fusion from T11 to L3.
. Anterior corpectomy and cage placement.
. Conservative management with a rigid thoracolumbosacral orthosis (TLSO).
. Laminectomy and decompression without fusion.
. Percutaneous balloon kyphoplasty.

Correct Answer & Explanation

. Conservative management with a rigid thoracolumbosacral orthosis (TLSO).

Explanation

A TLICS score of less than 4 (in this case: morphology=burst (2), neuro=intact (0), PLC=intact (0); total=2) indicates non-operative management. Conservative treatment with bracing or early mobilization is the standard of care for stable, neurologically intact thoracolumbar burst fractures.

Question 297

Topic: Thoracolumbar Spine & Deformity

According to Paley's principles, how is the ideal magnitude of the proximal valgus angle calculated when planning a pelvic support osteotomy?

. Maximum adduction angle + 15 degrees
. Maximum abduction angle + 15 degrees
. Neutral alignment (0 degrees of valgus)
. Maximum adduction angle + 30 degrees
. Exactly 45 degrees of valgus universally

Correct Answer & Explanation

. Maximum adduction angle + 15 degrees

Explanation

The proximal osteotomy must compensate for the maximum adduction of the hip and add an additional 15 degrees. This overcorrection accommodates normal pelvic tilt during gait and ensures solid ischial abutment.

Question 298

Topic: Thoracolumbar Spine & Deformity

During a pelvic support osteotomy for an adolescent with a neglected hip dislocation, the surgeon notes a fixed 30-degree hip flexion contracture. How should this deformity be addressed at the proximal osteotomy site?

. Incorporating 30 degrees of flexion into the osteotomy.
. Incorporating 30 degrees of extension into the osteotomy.
. Performing an isolated distal femoral extension osteotomy.
. Aggressive postoperative physical therapy without intraoperative bony correction.
. Releasing the posterior capsule of the hip.

Correct Answer & Explanation

. Incorporating 30 degrees of extension into the osteotomy.

Explanation

Hip flexion contractures are common in chronic dislocations and are addressed by incorporating extension into the proximal osteotomy. Adding an extension component compensates for the contracture and prevents an excessive anterior pelvic tilt during ambulation.

Question 299

Topic: Thoracolumbar Spine & Deformity

A 40-year-old patient with a 2.5 cm limb length discrepancy (LLD) due to a previous distal femoral fracture is scheduled for a standing long-leg alignment radiograph. The patient typically compensates for the LLD by flexing the contralateral knee and tilting their pelvis.

What is the most appropriate technique to ensure accurate alignment assessment and prevent compensatory mechanisms from affecting the measurements?

. Instruct the patient to stand naturally without any intervention
. Ask the patient to flex the contralateral knee to level the pelvis
. Place a lift of appropriate height under the shorter limb to level the pelvis
. Obtain the radiograph in a non-weight-bearing supine position
. Have the patient stand on one leg, bearing full weight on the longer limb

Correct Answer & Explanation

. Place a lift of appropriate height under the shorter limb to level the pelvis

Explanation

Correct Answer: CThe text clearly states that if there is a limb length discrepancy (LLD), the shorter limb should be elevated on blocks adjusted to the approximate discrepancy (Fig. 3-8). This technique prevents the patient from using compensatory mechanisms such as contralateral knee flexion, ipsilateral ankle equinus, pelvic tilt, and scoliosis, which can alter alignment and leg length measurements. These compensatory mechanisms cause uneven loading of the limbs and can lead to inaccurate radiographic assessment. Options A, B, and E describe scenarios where compensatory mechanisms would be present or exacerbated, leading to inaccurate measurements. Option D, while eliminating weight-bearing compensation, does not assess functional standing alignment.

Question 300

Topic: Thoracolumbar Spine & Deformity

A patient with a severe fixed abduction deformity of the right hip will typically develop which compensatory deformity to maintain a level gaze and forward progression during gait?

. Left pelvic drop
. Lumbar scoliosis convex to the left
. Lumbar scoliosis convex to the right
. Knee recurvatum on the right side
. Right ankle equinus contracture

Correct Answer & Explanation

. Lumbar scoliosis convex to the left

Explanation

A fixed right hip abduction deformity causes an apparent lengthening of the right leg. To place the right foot flat and compensate, the pelvis drops on the left, leading to a compensatory lumbar scoliosis that is convex to the left to keep the head centered.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page